(a) Field of the Invention
The present invention relates to a clock generator, and more particularly, to a clock generator that is substantially immune from the influence of manufacturing process, supply voltage, and temperature.
(b) Description of the Related Art
In an integrated circuit, the clock signal is an indispensable reference signal. The clock signal can be used as a reference signal when sampling input data, a reference clock for the arithmetic circuits, and so forth.
Generally, a clock signal used in an integrated circuit is generated from a an outside external quartz oscillator which generating a reference clock signal, and then to output the clock signal with a higher frequency by the phase lock loop of the integrated circuit according to the reference clock signal. However, although the method of generating the clock signal by the quartz oscillator can generate a more precise clock signal to be used by the integrated circuit, such a method still needs least one extra pin of the integrated circuit to receive the reference clock signal. That will cause a higher cost and hard to reduce the package area.